<script type="text/javascript">	
$(document).ready(function(){
$("#btn_AddToList").click(function(){
	alert($('input[name=List1]').val()); // Let me know the textbox's value
	$('input[name=List1]').val().appendTo('#List2');
	});			
});
</script>
<input name="List1" type="text">
<input type="button" id="btn_AddToList" value="Add">
<select id="List2">
<option>---</option>
</select>
<select name="List1">
<option>---</option>
<option>Test1</option>
<option>Test2</option>
<option>Test3</option>
<option>Test4</option>
<option>Test5</option>
<option>Test6</option>
</select>
<input type="button" id="btn_AddToList" value="Add">
<select id="List2">
<option>---</option>
</select>